On The Electromechanical Coupling Of Coaxial Cavity Filter And Design Of Dual-Circularly-Polarized Antenna

This research works are made with scientific projects. The work can be divided into two parts:The content of the frist part is on electromechanical coupling of coaxial cavity filter, in order to find the relationship between the structure parameters and the electric performance. The content of the second part is design of dual circularly polarized antenna, in order to settle the problem that "bei-dou" antenna work with compact size.The first study in the thesis is to find the relationship between structure parameters and the electromagnetic for coaxial cavity filter.Fristly, conception and intention of coupled field is introduced, purpose of research and actuality of development is summarized.Secondly, several methods of design of coaxial filter are discussed, by the design conception, a two-cavity coaxial filter and a four-cavity coaxial filter, can be worked with wide-band(1.3GHz-1.8GHz), has been designed, and the results of simulated are satisfied the designed target.Thirdly, several existing research methods of coaxial filter and its localization is discussed. After combine with lots of engineering experience, the coupled field models of coaxial filter which is supplied by one graduate school, are setted up by two ways that are finity element method and equivalent circuit method.Lastly, to find out the main structure parameters which affect the electric performance of filter, by engineering experience and analysis. Then find out the relationgship between the structure parameters and the electric performance.The second study in the thesis is design of a compact dual-circularly-polarized microstrip antenna, firstly, a compact dual circular polarization microstrip patch antenna is designed, the simulated results indicate that the VSWR of the antenna is less than 2, axial ratio of the antenna is less than 3dB, the HPBW is more than 100°. A prototype has been fabricated and tested, the measuring results are similar to the simulated results, he measured results show that this design method is valid and it can be applied in engineering. Secondly, in order to improve the plus of the antenna and amend the isolation of the two ports of the antenna, mend the antenna by use the lange-coupled as the feed net work. This method can improve the plus of the antenna and amend the isolation of the two ports of the antenna effectively by simulated analysis.